Adhesion pattern and prognosis studies of T4N0M0 colorectal cancer following en bloc multivisceral resection: evaluation of T4 subclassification.

In current TNM stage system, T4 lesions represent a complex group and should be considered to further optimize the classification. This study evaluates the significance of adhesion pattern in T4 subclassification based on prognostic analysis of T4N0M0 colorectal cancer following en bloc multivisceral resection (MVR). Prospectively collected data (1992-2004) were analyzed for 278 patients with stage T4N0M0 lesions following MVR for colorectal cancer. Patients were divided into inflammatory adhesion (IA) and malignant invasion (MI) groups based on adhesion to adjacent organs. Survival was evaluated by Kaplan-Meier and Cox proportional hazards regression analyses. MI was detected in 249 of 460 (54.1%) resected organs and in 159 of 287 (55.40%) patients undergoing MVR. Compared with IA group, patients in MI group showed no significant difference in clinicopathological data except tumor differentiation (P = 0.0376). Cox proportional hazards regression showed that MI was independently associated with overall survival among both colon (HR = 2.028; P = 0.0001) and rectal (HR = 0.451; P = 0.0002) cancer patients. Kaplan-Meier analysis showed that MI patients had a significantly higher MVR compared with IA patients (colon cancer: P = 0.0018; rectal cancer: P = 0.0116). In conclusion, MI was validated as an adverse prognostic factor for stage T4N0M0 colorectal cancer following MVR suggesting that it may be classified as a T4-subgroup in order to reinforce practice guidelines.